Too much water

Water environment

Water quality

Too little water

Texas Legislative Background• Freshwater inflow needs for bays & estuaries (1980s)• Senate Bill 1: water resource planning & management (1997)• Senate Bill 2: the science bill (2001)– Instream flow data collection and evaluation program– Methodologies to determine flow conditions in Texas rivers

and streams necessary to support a sound ecological environment

• Senate Bill 3: the implementation bill (2007)– The who, when, and how of eflow implementation in Texas – TCEQ must adopt the recommended standards by June 2011

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The study of ecology requires (and adds) complexity and nuance

Blue Line

3D stream

The real thing

Flow

Biota Habitat

River Continuum Concept

the natural flow regime

Magnitude

Timing

Duration

Rate of Change

Not depicted: frequency

flow components

(NRC 2005)

An example instream flow prescription

Big Sandy Creek near Big Sandy, Tx

An Environmental Flow RegimeUSGS Gage 08019500, Big Sandy Creek near Big Sandy

Season Subsistence Base Pulse Winter 20 cfs 73 cfs 1 per season

Trigger: 358 cfs Volume: 5,932 af Duration: 10 days

Spring 9 cfs 33 cfs 2 per season Trigger: 313 cfs Volume: 5,062 af Duration: 13 days

Summer 8 cfs 15 cfs 1 per season Trigger: 50 cfs Volume: 671 af Duration: 6 days

Fall 8 cfs 22 cfs 2 per season Trigger: 130 cfs Volume: 2,189 af Duration: 9 days

cfs = cubic feet per second , af = acre-feet

www.tceq.com

TCEQ Water Rights Points

USGS Gages

NHDPlus

Data Sources

Bringing the Data Together

USGS Water Resources Region 12

TCEQ’s NeedWater Withdrawals Not Near Gages

How to assess the contribution of a withdrawal on a tributary to an environmental flow defined on the main stem river?

Gages on the Trinity River in the DFW Metroplex

River Reach between Gages

Trinity River Branches

West Fork

Elm Fork

Trinity River

Drainage Area = 2459 sq. miles

Drainage Area = 6106 sq. miles

Mean Annual Flows

West Fork, 54% flow

Elm Fork, 46% flow

Trinity River

Elm Fork Attributes

Length = 28.39 km Mean Flow = 670 cfs Mean Velocity = 1.52 ft/sec

Max Elev = 130.93 m Min Elev = 121.25m Slope = 0.34m/km or 0.034%

Trinity River Attributes

Length = 9.39 km Mean Flow = 1493 cfs Mean Velocity = 1.86 ft/sec

Max Elev = 121.25 m Min Elev = 118.78m Slope = 0.26m/km or 0.026%

Kinematic and Dynamic Waves

Finding Pulse Lag Times in WiSKI

12 Hours

Image courtesy of Matt Ables, Kisters

Trinity River at Dallas

Elm Fork of Trinity River at Carrollton, 12 hours earlier

Two time scales

Analytical Solution of the Kinematic Wave

Wave Celerity vs. Flow Velocity

• Wave celerity = 5/3 * flow velocity Length (km) Flow Velocity

(ft/s)Wave Celerity (ft/s)

Travel Time (hours)

Elm Fork 28.39 1.52 2.53 10.23

Trinity 9.39 1.86 3.10 2.76

TOTAL 12.99

Good agreement between travel time based on kinematic wave celerity and that based on time series data comparisons in Wiski.

Muskingum-Cunge Method

Kinematic wave plus some dynamic wave effects

Muskingum-Cunge X ParameterUsing NHD Mean Annual Flow

Elm Fork near Carrollton

Trinity at Dallas

Q 652.7 cfs 1496.5 cfs

B 80 ft 170 ft

ck 2.53 ft/s 3.10 ft/s

S0 0.00034 ft/ft 0.00026 ft/ft

Δx 93143 ft 30807 ft

X 0.449 0.323

Using USGSMean Annual Flow

Elm Fork near Carrollton

Trinity at Dallas

Q 841.7 cfs 1804.3 cfs

B 80 ft 170 ft

ck 2.53 ft/s 3.10 ft/s

S0 0.00034 ft/ft 0.00026 ft/ft

Δx 93143 ft 30807 ft

X 0.434 0.286

Trinity River Elm Fork

Muskingum-Cunge Method in HEC-HMS

HEC-HMS

HEC-HMS Model of Brushy Creek in Round Rock